TY - JOUR
T1 - Enhanced flux pinning via chemical substitution in bulk superconducting Tl-2212
AU - Paranthaman, M.
AU - Foldeaki, M.
AU - Balzar, D.
AU - Ledbetter, H.
AU - Nelson, A. J.
AU - Hermann, A. M.
PY - 1994
Y1 - 1994
N2 - The flux-pinning characteristics in both pure and doped superconducting Tl2Ba2CaCu2O8 (referred to as Tl-2212) systems were studied via DC magnetic hysteresis as well as flux-penetration and flux-expulsion measurements. At 5 K between 0 and 4.5 T, the 5 at.% Mg-doped Tl-2212 (Tl, Mg-2212) samples displayed enhanced pinning as demonstrated by a field-dependent increase of the magnetic critical current density Jc by 18-25% as compared with the pure Tl-2212. Excess Mg (10-15 at.%), however, is deleterious. Rietveld refinement of the X-ray diffraction pattern showed Mg on the Tl sites. AES analysis showed part of the Mg appearing on grain boundaries. Both Tl-2212 and Tl, Mg-2212 displayed a persisting remanent magnetization Mrem with a higher value for Tl, Mg-2212, as well as an asymmetrical behaviour between flux expulsion and flux penetration. The flux-creep activation energies are higher for flux expulsion than for flux penetration in both samples; Tl, Mg-2212 displayed higher individual values. Our results demonstrate an increase in both intrinsic pinning and lock-in transition of flux lines as a result of increased density of atomic-size structural defects via Mg doping in Tl-2212.
AB - The flux-pinning characteristics in both pure and doped superconducting Tl2Ba2CaCu2O8 (referred to as Tl-2212) systems were studied via DC magnetic hysteresis as well as flux-penetration and flux-expulsion measurements. At 5 K between 0 and 4.5 T, the 5 at.% Mg-doped Tl-2212 (Tl, Mg-2212) samples displayed enhanced pinning as demonstrated by a field-dependent increase of the magnetic critical current density Jc by 18-25% as compared with the pure Tl-2212. Excess Mg (10-15 at.%), however, is deleterious. Rietveld refinement of the X-ray diffraction pattern showed Mg on the Tl sites. AES analysis showed part of the Mg appearing on grain boundaries. Both Tl-2212 and Tl, Mg-2212 displayed a persisting remanent magnetization Mrem with a higher value for Tl, Mg-2212, as well as an asymmetrical behaviour between flux expulsion and flux penetration. The flux-creep activation energies are higher for flux expulsion than for flux penetration in both samples; Tl, Mg-2212 displayed higher individual values. Our results demonstrate an increase in both intrinsic pinning and lock-in transition of flux lines as a result of increased density of atomic-size structural defects via Mg doping in Tl-2212.
UR - http://www.scopus.com/inward/record.url?scp=0028408104&partnerID=8YFLogxK
U2 - 10.1088/0953-2048/7/4/008
DO - 10.1088/0953-2048/7/4/008
M3 - Article
AN - SCOPUS:0028408104
SN - 0953-2048
VL - 7
SP - 227
EP - 233
JO - Superconductor Science and Technology
JF - Superconductor Science and Technology
IS - 4
M1 - 008
ER -